The present invention relates to a valve mechanism for controlling fluid flows when refueling a fuel tank provided with a filler neck, having: a housing in which there are constructed a first opening for connecting an operational vent line coming from the top side of the fuel tank and a second opening for connecting a fuel vapor recycling line coming from a compensating tank and/or collecting tank; a valve member which is mounted movably in the housing between a first and a second position and has at least one sealing surface; a valve seat which is arranged in the housing between the openings and cooperates with the sealing surface(s) of the valve member in order, in the first position, to set up a fluid connection between the first opening and the second opening and, in the second position, to interrupt the flow connection; and actuating means for the valve member in order to move the latter from the first position into the second position.
Such a valve mechanism is known from U.S. Pat. No. 5,404,906.
The invention relates, in particular, to such a valve mechanism which is intended for use in a refueling system, which has the following components:
a fuel tank with a filler neck, PA1 a compensating tank which is connected to the fuel tank via an ascending pipe, PA1 a collecting tank for fuel vapors which is connected, for its part, to a vent line of the compensating tank, and PA1 an operational vent line which comes from the top side of the fuel tank and is open during operation but closed during refueling, in order to fuel up in the upper region of the fuel tank an air reservoir which after refueling and upon opening of the operational vent line starts to be filled up by the fuel continuing to run from the filler neck, and thus provides the overfill prevention function for the filler neck which is known in the prior art.
It is the object of the invention to create a valve which incorporates all the fluid control functions required to operate such a refueling system as described above.